NEW YORK — JPMorgan Chase & Co. Chief Executive Officer Jamie Dimon had his pay cut in half after the lender concluded reviews of an investment unit's trading losses by finding he bears responsibility for the blunders.

Dimon's compensation for 2012 was $11.5 million, compared with $23 million a year earlier, the New York-based bank said Wednesday on its website. His $1.5 million salary went unchanged while incentive awards fell to $10 million, all in restricted shares that vest over three years, from $21.5 million.

JPMorgan is seeking to rebuild investor trust after losing more than $6.2 billion in the first nine months of 2012 on bets by British trader Bruno Iksil, nicknamed the London Whale because his positions were so big. Dimon, 56, said Wednesday that the bank was almost done with losses at its chief investment office and won't disclose the size of future declines.

"Mr. Dimon bears ultimate responsibility for the failures that led to the losses in CIO and has accepted responsibility," the bank said after spending about eight months reviewing what Dimon has called "egregious mistakes" at the chief investment office.

The firm also decided to push back by as much as 18 months the vesting of 2 million stock options that Dimon got in January 2008. Delays in the awards, which had an exercise price of $39.83, will give the lender more time to fix weaknesses underlying the trading loss, the firm said.

The debacle has prompted lawsuits, probes in the United States and abroad and this week led to the first regulatory sanctions, as banking watchdogs found internal-control "deficiencies."

The loss at JPMorgan, considered one of the industry's best-managed firms after remaining profitable during the credit crisis, also spurred lawmakers to attempt to tighten trading curbs included in the 2010 Dodd-Frank Act. The chief investment office was supposed to manage excess cash while minimizing risk. The unit used credit derivatives as part of a hedging strategy, and the trades became so large the bank couldn't easily unwind them.

JPMorgan on Wednesday released three documents tied to the bets: a disclosure on Dimon's compensation, a 129-page report from a task force led by Michael Cavanagh, co-head of the firm's corporate and investment bank, and a statement from the review committee of the lender's board.

Dimon failed by trusting information given to him by senior managers, according to the task force.

Executives who have since been reassigned or departed were blamed for breakdowns contributing to the loss, including former Chief Investment Officer Ina Drew, Barry Zubrow, ex-head of companywide risk management, and former Chief Financial Officer Doug Braunstein.

Dimon "could have better tested his reliance on what he was told," the firm said. "More should have been done regarding the risks, risk controls and personnel associated with CIO's activities, and Mr. Dimon bears some responsibility."

The bank said its review of Dimon took into account his decisions to replace senior managers, efforts to claw back their pay and the formation of a team to examine what went wrong. The CEO had initially dismissed news accounts of the trading position as a "tempest in a teapot."

"Once Mr. Dimon became aware of the seriousness of the issues presented by CIO, he responded forcefully by directing a thorough review and an extensive program of remediation," according to the report.

The bank said separately today that fourth-quarter profit rose 53 percent to $5.69 billion as mortgage revenue climbed. Dimon, who is also chairman of the board, wasn't included in deliberations on his pay, he told reporters on a conference call after earnings were released.